1. Field of the Invention
The present invention relates to a heat sensitive switching device which turns on at higher than the specific temperature.
2. Description of the Prior Art
A thyristor having pnpn junctions has been known as means for switching from the OFF state to the ON state by a specific electrical or optical signal.
These conventional thyristors can be used only in a range of the temperature to prevent the lowering of the OFF voltage caused by rising junction temperature or to prevent the turn-on caused by heating.
The heat sensitive switching device of the invention is a switch which changes from the OFF state to the ON state when the temperature rises over the specific temperature.
The temperature to extinguish the OFF state by raising the temperature is higher than the rated maximum junction temperature defined for the conventional thyristors. Accordingly, the conventional thyristor has been difficult to switch at relatively low temperature because it has been required to increase the applicable power limit (or allowable loss) and accordingly, the conventional thyristor has been formed to maintain the OFF voltage at a temperature as high as possible.